import launch
import launch_ros 
from ament_index_python.packages import get_package_share_directory
import os
import launch_ros.parameter_descriptions 

def generate_launch_description():

    urdf_package_path=get_package_share_directory('fishbot_description')
    default_urdf_path=os.path.join(urdf_package_path,'urdf','first_robot.urdf')
    default_rviz_config_path=os.path.join(urdf_package_path,'config','display_robot_model.rviz')

    action_declare_arg_mode_path=launch.actions.DeclareLaunchArgument(
        name='model',default_value=str(default_urdf_path),description='jia zai wen jian lu jing'
    )

    subsitutions_command_result=launch.substitutions.Command(['xacro ',launch.substitutions.LaunchConfiguration('model')])
    robot_description_value=launch_ros.parameter_descriptions.ParameterValue(subsitutions_command_result,value_type=str)


    action_robot_state_publisher=launch_ros.actions.Node(
        package='robot_state_publisher',
        executable='robot_state_publisher',
        parameters=[{'robot_description':robot_description_value}]
    )

    action_joint_state_publisher=launch_ros.actions.Node(
        package='joint_state_publisher',
        executable='joint_state_publisher',
    )

    action_rviz_node=launch_ros.actions.Node(
        package='rviz2',
        executable='rviz2',
        arguments=['-d',default_rviz_config_path]
    )

    return launch.LaunchDescription([
        action_declare_arg_mode_path,
        action_robot_state_publisher,
        action_joint_state_publisher,
        action_rviz_node,

    ])